The present invention relates to an automatic train control system of the type disclosed in U.S. Pat. No. 4,023,753, whose disclosure is incorporated herein by reference, and more particularly to a facility for fail-safe data transmission between trackside equipment of a guideway and vehicles moving therealong.
Facilities of this kind are used, for example, to control trains on lines equipped with continuous track conductors. The rules to be observed in such train control systems, including those concerning the cyclic code to be used to protect the data transmission, are contained in the specification on the result No. 6A of the work of the Committee A46 of the Office for Research and Experimentation, ORE, of the International Union of Railways, UIC (see page 17, item 7, for example), and thus are known to those skilled in the art.
In continuous automatic train control, all vehicles located within a relatively long section of line are controlled from a center. The data transmission takes place in both directions via a permanent connection. If a transmitter or a receiver fails, this will be detected immediately by the nonappearance of given data messages or of information contained therein, and communicated to the respective counter station, i.e., the center or the vehicle.
Since the equipment of a line with continuous track conductors is very expensive, it is only suitable for specially improved, high-speed main lines for the time being.
On other lines, data transmission takes place only at discrete points and to a limited extent (intermittent type of control system), e.g., to transmit signal aspects in the inductive signaling system (Indusi), or in car-number indentification systems (cf. article by H. Gotz, "Systeme zum automatischen Lesen von Eisenbahnwagennummern", Siemens-Zeitschrift 43 (1969), No. 7). It would be desirable if additional information, such as track gradients, distances to signals, and maximum safe speeds, i.e., information which could be stored locally at the trackside and would require no expensive daata link to a center, could be communicated to the vehicles by means of intermittent transmission facilities.
However, this presents the problems of protecting the data to be transmitted and, in the absence of a permanent connection, of detecting failures in the equipment arranged along the track at irregular intervals.